Is the Phone Outdated?

A description of myself these days: A Recruiter who is busy, not recruiting amazing candidates, but recruiting clients, searching for jobs.

It's a very interesting thing to be searching for jobs that I myself don't have any desire to do, but I am still working hard to find them. The trick is making connections and seeing if a particular company has any open spots.

Once I've exhausted friends, I have turned to a database of nearly 400 companies in the NYC area to start calling. 90% of the phone calls I make result in getting a voicemail, even if I already have the name of the hiring manager. The rest have all told me that they only do in-house recruiting, and a few have actually requested to see my company's materials for "in the future." I have sent materials, and will occasionally check back in, develop the relationships, and see if business can ever be done.

All of this has led me to ask the question - am I wasting my time?

Which has a better value? Cold Calling and changing up Sales Pitches OR researching and connecting on Twitter/LinkedIn?

Do recruiters out there have any advice of what's worked and what hasn't? Tips?